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hbruun

Losing JPG quality when saving

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I use Paint.net a bunch and love it.

Today I ran into an odd thing though... I was editing an existing JPG image and was doing some cropping to it and then saving the cropped image. I noticed that the new image was losing significant quality. I have quality set to 100%. Any ideas?

I'm attaching two pictures to demonstrate the issue. One is a portion of the image that I'm starting with, the other is a capture showing how the save operation loses quality... the most obvious portion is the fairly bright red horizontal line in the picture (ends up looking much dimmer in the new image).

23484_bae3907124cdc936fb5e42c50a586dba

23484_1ebbf922c514c65a878375965a05b773

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PNG loses the quality too (I tried that earlier)

Other tools such as FastStone Image Viewer and Gimp can handle saving this file without losing the quality. In the case of FastStone I get to preserve the quality by selecting what they call a 'Photometric = RGB'

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I would have agreed with you both until yesterday.

'I Like Pi', I see that you created a test.png from my test.jpg... put them side by side and you'll see that the colors got changed significantly.

Brewster, I've tried both 'Autodetect' and 32-bit for the png settings and the same color changes occur.

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It is not a browser issue as the color changes become apparent immediately (even in Paint.net's save preview window).

I placed the original test.jpg next to 'I Love Pi''s test.png to make it more clear how things change during the save of the new file (attached here).

23484_116fad0146129e8287e059ee51487e13

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It is a browser issue.

Here's what I see in Firefox 3.1 b2 :

szhxndxksmmwshu3.png

If I put both in two layers in PDN and select Difference blending mode, all that I can see is black.

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:) I agree that the browsers don't help the situation. Firefox 3.1 b2 shows the PNG file as a darker red than IE (the various paint programs do not have that problem with the PNG).

So I still think there is room for improvement in Paint.net since the PNGs that can be created are being displayed differently in the various browsers (not Paint.net's fault) and the JPGs created lose accuracy/quality. I'm calling it an improvement since other paint programs have found a way to deal with it.

I'm including screen shots how how two others handle it with no loss of quality (their JPG save options).

23484_2c4e4ab695933bae5363748be83929ff

23484_f91dc047440409f7e83e2daf914b9f47

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The probably also have their own JPEG codecs, instead of using the minimally configurable ones provided by the system (in this case, .NET and GDI+ or WIC). Lots and lots and lots more code there.

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